The present invention is drawn to a method for excavating and constructing monolithic continuous straight or circular structural walls and an equipment for carrying out the method.
A method is already known in the prior art which consists of digging a trench for the structural wall, substaining the walls of the trench by introducing mixtures, usually with bentonite, and then inserting a diaphragm made of adjacent prismatic elements with a rectangular section.
The main drawback of such a technique is that the elements of the diaphragm, being simply put near each other, do not guarantee a safe hydraulic sealing nor the complanarity of the various elements. The foregoing results in settings when underground stresses occur.
Moreover, when the walls of the trench are kept up by bentonitic mixtures, several yard equipment, usually very bulky, are required for making and storing the bentonite mixtures.
A further problem occurs when the excavated soil is polluted with bentonite. Dumps are needed together with transportation means provided with watertight dump boxes to dispose of the soil.
The foregoing technique is not only used for executing straight stuctural concrete walls, but also for realizing wells and therefore structural walls with a circular shape. In this second case the method consists in executing, along the circumference of the wall, a sequence of reinforced concrete diaphragms. Such diaphragms are casted into trenches that are substained by bentonitic mixtures.
The diaphragms are mainly executed in sequences, with opening and closing diaphragms alternatively fitted.
The main drawback of this excavating technique is that the diaphragms are never perfectly vertical, so that it is impossible to execute a structural junction between the single diaphragms. So a further problem is that such diaphragms guarantee the well to be functional only down to the level where they are perfectly positioned along the circumference of the wall.
At deeper levels, due to the misalignment with the vertical line, the diaphragms work as isolated elements in the ground, being stressed by bending and shearing stresses.